Color photographic process



United States Patent U.S. C]. 96-55 7 Claims ABSTRACT OF THE DISCLOSURE Color development in the presence of a color coupling compound of a partially bleached silver image still containing silver nuclei, by means of an alkaline aqueous developing medium containing as color developing agent a hydrazone compound dissolved therein.

This invention relates to color photography, and more particularly to a color development process.

According to this invention a method is provided for the production of photographic images in color.

The present invention is more particularly directed to a method of producing a color image by color-developing a partially bleached silver image in a photographic element, which may or may not be sensitized, in the presence of a coupling component to form a dye.

Said method is based on the discovery that a silver image, which is partially oxidized to a silver salt image as described hereinafter, can oxidize certain weakly reducing hydrazone compounds and that by the oxidizing power of the said silver salt image in alkaline medium oxidatively coupling takes place between the hydrazone compound and a suitable coupling component to form an azino dye.

The hydrazone compounds used as developers according to the present invention can be characterized by the wherein n is 1, 2 or 3, and are more particularly represented by the following structural formulae:

One substituent or more substituents with ionic character make the hydrazone compound soluble in an aqueous alkaline medium,

Z represents the non-metallic atoms necessary to complete a 5- or 6-membered heterocyclic nucleus, alone or forming part of a condensed ring system,

R is hydrogen or an acyl radical, such as acetyl,

R is a -CONH group or a -SO X group, wherein X represents a hydroxyl group, an amino radical, an aliphatic hydrocarbon radical, an aryl radical, or a heterocyclic radical, which radicals preferably are substituted with one or more hydrophilic substituents e.g. a carboxyl or sulpho group,

R is a hydrogen atom, an alkyl radical, or an radical,

R is a hydrogen atom, an alkyl radical, or an aryl radical,

R is an amino radical, a heterocyclic radical, or a hydrocarbon radical e.g. an alkyl radical, or an aryl radical, including e.g. a halogen-, alkoxyor hydroxy-substituted aryl radical,

Each of R and R (the same or different) represents a hydrogen atom or a substituent radical such as a dialkylamino, carbethoxy, halogen, cyano, alkoxy, alkyl, including haloalkyl, such as trifiuoromethyl, or an aryl radical, or represent together the atoms necessary to close a 5- or 6-membered homocyclic ring, and

Y represents the non-metallic atoms necessary to complete a nitrogen-containing heterocyclic nucleus.

Hydrazone compounds analogous to the compounds of said general Formulae A, B, C and D are described in our cognate U.S. patent application 71,117, now U.S. Patent 3,245,785 and in our U.S. patent application 296,- 942 now abandoned. The greater part of the hydrazone compounds exemplified therein are, however, not soluble in aqueous alkaline medium and are of the non-migratory type and can therefore not be applied to the process according to the present invention.

0n replacing, however, the long aliphatic chain by a short one, e.g., by methyl or ethyl and/or on introducing several groups of ionic nature, such as carboxyl groups or sulpho groups, these compounds can be used in dissolved state.

Some detailed preparations of compounds according to the above general Formulae A, B, C and D suitable for use in the process of the present invention are given hereinafter:

PREPARATION 1 3 methyl 2 benzothiazolone 4' carboxyphenylsulphonylhydrazone having the formula:

first with water and then with warm acetonitrile. Melting point: above 260 C.

PREPARATION 2 1,4 dimethyl 2 quinolone 3' carboxy 4' droxyphenyl-sulphonylhydrazone of the formula:

is prepared according to the'following steps:

(a) Preparation of 3-carboxy-4-hydroxyphenylsulphonyl hydrazide To cos. (0.3 mole) of hydrazine hydrate in 120- ccs. of dioxan a solution of 14.2 g. (0.06 mole) of 3-carboxy- 4-hydroxyphenylsulphonyl chloride in 200 ccs. of dioxan is dropwise added. The mixture is stirred for 2 hours at C. An oil layer is formed, which is separated and then stirred for 2 hours in the presence of 5 N hydrochloric acid. The hydrazide, which has become solid, is washed first with water and then with acetonitrile, whereupon it 10 is sucked off. Melting point: 230 C. (with decomposition). Recrystallization from water does not change the melting point.

(b) Preparation of 1,4-dimethyl-2-quinolone-3-carboxy- 4'-hydroxyphenylsulphonyl-hydrazone PREPARATION 3 3 methyl 2 benzothiazolone-3'-carboxy-4'-hydroxyphenylsulphonyl-hydrazone of the formula:

C=NNHS 0 OH N (EH:

is prepared as follows:

A mixture of 3.07 g. (0.01 mole) of 1-methyl-2-methylthiobenzothiazolium methylsulphate and 2.32 g. (0.01 mole) of S-(hydrazinosulphonyl)-salicylic acid is stirred for min. at 40 C. in 100 ccs. of pyridine. After dissolution of the reagents the reaction is allowed to proceed for 12 hours at 20 C. The precipitate formed is washed first with water, then with 1 N hydrochloric acid and finally once again with water. The hydrazone obtained is purified by washing with acetonitrile. Melting point: 260 C. (with decomposition).

PREPARATION 4 Piperidino p carboxyphenylsulphonyl-3,4-dimethoxybenzamidrazone of the formula:

CHE-CH2 GHQ-CH:

NNHSOz-C 0 on is prepared as follows:

4 PREPARATION 5 10 methyl 9 acridone 4' carboxyphenylsulphonylhydrazone of the formula:

N-NH -SO: COOI-I is prepared as follows:

3.67 g. (0.01 mole) of 9-methylthio-10-methyl-acridinium iodide, prepared according to preparation 7 of our U.S. continuation-in-part application 342,305, and 2.16 g. (0.01 mole) of 4-(hydrazinosulphonyl)-benzoic acid, are allowed to react at 20 C. in 35 ccs. of pyridine for 7 days. The mixture is poured onto ice and the precipitate formed is sucked off, whereupon it is washed with water. The product is recrystallized from a mixture of ethyl acetate and n-hexane. Melting point: 195 C. (with decomposition). The melting point remains the same after a further recrystallization from isopropanol.

PREPARATION 6 1 methyl-Z-phenyl-4-quinolone-3'-carboxy-4'-hydroxyphenylsulphonyl-hydrazone of the formula:

is prepared according to the following steps:

(a) Preparation of fl-phenylamino-ethyl cinnamate A mixture of 261 ccs. (1.5 mole) of benzoyl ethyl acetate, 140 ccs. (1.5 mole) of aniline and 5 ccs. of a concentrated solution of hydrogen chloride is stored in vacuum for 10 days at 20 C. in the presence of concentrated sulphuric acid as desiccant. The precipitate formed is sucked off and washed with methanol. The product is recrystallized from methanol. Melting point: 71 C.

(b) Preparation of 2-phenyl-4-quinolinol 195 g. (0.73 mole) of the above B-phenylamino-ethyl cinnamate are added while stirring to 2.2 liter of diphenyl ether heated at 250 C. After stirring for another 10 minutes at 250 C. the reaction mixture is allowed to cool. The precipitate formed is sucked off and washed with ether. The melting point of 2-phenyl-4-quinolinol is 250 C.

(c) Preparation of 2-phenyl-4-chloro-quinoline 260 g. (1.2 mole) of 2-phenyl-4-quinolinol are added to 321 ccs. (3.6 mole) of phosphorus oxychloride and heated for 2 hours at C. After having been cooled, the reaction mixture is poured onto ice. The formed precipitate is sucked ofi? and washed with water. After recrystallization from diluted ethanol, 2-phenyl-4 chloroquinoline is obtained, which melts at 60 C.

(d) Preparation of 1methy12phenyl-4-chl010- quinolinium methylsulphate 47.8 g. (0.2 mole) of 2-phenyl-4-chloro-quinoline and 56 cc. (0.6 mole) of dimethyl sulphate are heated together for 2 hours at C. After having been cooled the reaction mixture is washed thoroughly with ether. The remaining oil is used as such in the following reaction step.

(e) Preparation of l-methyl-Z-phenyl-4-quinolone-3'- carboxy-4'-hydroxyphenylsulphonyl-hydrazone 3-carboxymethyl-Z-benzothiazolone methylsulphonylhydrazone of the formula:

JJHPCOOH is prepared according to the following steps:

(a) Preparation of Z-methylmercapto-(3-carboxmethyl)- benzothiazolium bromide g. (0.55 mole) of 2-methylthio-benzothiazole, prepared according to R. Riemschneider, Monatsh. Chem. 91 1960) 626, and 22.8 g. (0.165 mole) of bromoacetic acid are refluxed for 70 hours in 50 ccs. of dry benzene. The precipitate formed is sucked off and washed first with ethanol and then with ether. The quaternary salt obtained melts at 180 C. (with decomposition).

(b) Preparation of 3-carboxymethyl2benzothiazolonemethylsulphonyl-hydrazone 8 g. (0.025 mole) of the above quaternary salt and 2.75 g. (0.025 mole) of methylsulphonyl hydrazide are heated for 18 hours at 60 C. in 100 ccs. of pyridine. After evaporation in vacuum, water is added whereupon the mixture is acidified with hydrogen chloride. The precipitate formed is sucked off and recrystallized twice from a mixture of equal parts of ethanol and water. The hydrazone obtained melts at 200 C. (with decomposition).

PREPARATION 8 3 methyl-Z-benzothiazolone-4'-sulphophenylsulphonylhydrazone of the formula:

is prepared according to the following steps:

(a) Preparation of 3-methyl-2-benzothiazolone-4'-fluorosulphonylphenylsulphonyl-hydrazone (b) Preparation of 3-methyl-2-benzothiazolone-4'-sulphophenylsulphonyl-hydrazone 20.5 g. (0.05 mole) of the above fluorosulphonyl compound are dissolved in 250 ccs. of 1 N sodium hydroxide 6 by heating on a Water bath. The reaction mixture is filtered and then acidified with hydrogen chloride. The precipitate is sucked olf and washed with water, Whereupon it is recrystallized from a mixture of equal parts of ethylene glycol monomethyl ether and water. Melting point: above 260 C.

PREPARATION 9 3-rnethyl-6-methoxy 2 benzothiazolone-3'-carboxy-4'- hydroxy-phenylsulphonylhydrazone monohydrochloride of the formula:

COOH

H CI=N NHSOR is prepared according to the following steps:

(a) Preparation of 2-amino-3-methyl-6-methoxybenzothiasolium iodide 10.8 g. (0.06 mole) of 2-amino-6-methoxybenzothiazole, 15 ccs. of methyl iodide and 60 ccs. of acetone are refluxed for 1 h. Already during the reaction, the formed quaternary salt starts to settle. After having been cooled, the precipitate is sucked off and washed with acetone. Yield: 19.2 g. Melting point: above 260 C.

(b) Preparation of 2-nitrosimino-3-methyl-6-methoxybenzothiazole From the iodide prepared under (a), the base is set free and extracted by stirring 21 g. (0.065 mole of said iodide in a mixture of 100 ccs. of concentrated ammonium hydroxide and 100 ccs. of ether. After the evaporation of the ether, the resulting oil is dissolved in ccs. of acetic acid. Nitrosation is then carried out at 15 C. with a solution of 39 g. of sodium nitrite in 80 ccs. of water. After having been stirred for l h., the formed precipitate is sucked off and Washed with ether. Yield: 14.5 g. Point of decomposition: 190 C.

(c) Preparation of 3-methyl-6-methoxy-benzothiazolethione(2) 14.5 g. of the above nitroso compound are portionwise added at 80 C. to a mixture of 21 g. of phosphorus pentasulphide, 250 ccs. of pyridine and 60 cc. of piperidine. Thereupon the reaction mixture is heated for 3 h. by refluxing, in order to terminate the reaction. Finally, the reaction mixture is poured on ice. After having been sucked off, the formed precipitate is recrystallized from petroleum naphtha. Yield: 10.8 g. Melting point: 118 C.

(d) Preparation of Z-methylmercapto-3-methyl-6- methoxy-benzothiazolium iodide 10.8 g. (0.051 mole) of said benZothiazole-thione (2) is heated for 2 h. in 75 ccs. of ethanol and 20 ccs. of methyliodide by refluxing. After having been cooled in ice, the formed precipitate is sucked off. Yield: 16.5 g. Point of decomposition at about C.

(e) Preparation of 3-methyl-6-methoxy 2 benzothiazolone 3' carboxy 4' hydroxy-phenylsulphonylhydrazone monohydrochloride 35.3 g. (0.1 mole) of the above methylmercapto compound and 23.2 g. (0.1 mole) of 3-carboxy-4-hydroxyphenylsulphonyl hydrazide, prepared as described in preparation 2(a) are allowed to react for 24 h. in 150 ccs.

of pyridine at 60 C. Thereupon, the reaction mixture is poured in a mixture of 500 g. of ice and 150 ccs. of strong hydrochloric acid. The formed precipitate is fil tered by suction, boiled with water and washed with ethanol. Yieldz'24 g. Point of decomposition at about 230 C.

Contrary to other known developers of the type of aromatic primary amino compounds, aromatic hydrazines or hydrazones of the type of our compounds, :but wherein R and R are both hydrogen, the hydrazone compounds used in the present invention are very soluable in aqueous alkaline medium and very stable to aerial oxidation. They can, however, be oxidized by a bleached silver image, the silver salts of which have a solubility product not lower than l at 25 C .and which still contain silver nuclei. Thus it has been stated that not completely bleached silver images built up by silver bromide and/ or silver iodide and silver nuclei do not oxidize in a suflicient degree to permit the oxidative coupling reaction of the said hydrazone compounds with a color coupler. Thus it has further been stated that in the case the bleaching time was very long, no coupling could be obtained.

Good results are obtained with silver images the bleaching of which is stopped at the moment no silver can still be detected with the naked eye.

For practical purposes the solubility of the silver salts formed on bleaching may not be so great that said salts can be bleached out in the developing bath. So these salts have a solubility product preferably not greater than at 25 C.

Considering the foregoing, preferably CuCl FeCl K Fe(CN) a mixture of Na Cr O- and hydrogen chloride, a mixture of K S O and hydrogen chloride or a mixture of CuSO and hydrogen chloride are used as oxidative substances in the color developing process according to the present invention for bleaching the silver image.

The coupling components are preferably incorporated in the photographic material and are preferably on the non-migratory type. Suitable coupling components are found in the group of the classical color couplers such as the color couplers of the naphthol-, phenol-, pyrazoloneor ketomethylene type. In principle, however, all compounds containing a sufliciently reactive hydrogen atom or the so-called strongly nucleophilic organic compounds can be used for the coupling. Examples of such compounds are described in Analytical Chemistry: 33 (1961), 722-725; 33 (1961), 1574-1579; 32 (1960), 1434-1436; 33 (1961), 93-96 and Chemist-Analyst 50 (1961), 68-69.

The color development is carried out in an alkaline medium preferably at a pH not lower than 8.

According to one embodiment, the method of producing a color image fast to light comprises the steps of exposing a photographic material containing light-sensitive silver halide to a color image, developing said material in a black-and-white developer, partially bleaching the obtained silver image to such an extent that together with the formed silver salts still silver nuclei are present and silver salts are formed having a solubility product not lower than 10- and not higher than 10- at 25 C., developing the bleached silver image with an alkaline aqueous solution containing a suitable color coupler and a hydrazone compound corresponding to one of the mentioned general formulae, fixing and rinsing the developed material.

According to a preferred embodiment, however, the color coupler is present in non-migratory form in the silver halide emulsion layer. Thus it is possible to obtain a color reproduction in complementary colors of a colored original by using a multilayer photographic color material, which contains a red-sensitive silver halide emulsion layer, a green-sensitive silver halide emulsion layer, and a blue-sensitive silver halide emulsion layer; the redsensitive emulsion layer containing in non-migratory form a color coupler capable of forming a cyan dye on development with a hydrazone compound of the type cited above, the green-sensitive emulsion layer containing in non-migratory form a color coupler capable of forming on development a magenta dye with the same hydrazone compound, the only blue-sensitive emulsion layer containing in non-migratory form a color coupler capable of forming a yellow dye with the same hydrazone compound. So, according to the last mentioned embodiment, color positives which are very fast to light can be obtained starting from color negatives.

In the multilayer photographic color material a yellow filter layer may be present between the blue-sensitive emulsion layer and the greenor red-sensitive emulsion layer.

After black-and-white development and fixation, the processing of the material may be interrupted and the further processing steps may be carried out in full daylight without harm to the image quality (see Example 3).

Although the process according to the present invention is especially suited for producing color reproductions in complementary colors, true direct positive color reproductions can be made, e.g., by using the positive silver images obtained by the method of producing photographic black-and-white reversal images according to William L. Jolly, J. Chem. Educ. 39 (1962), 83.

This process can be summarized in the following steps:

A multilayer color material as described above is exposed to a color original, and black-and-white developed.

The silver metal of the negative silver image is dissolved in an aqueous bleaching solution containing 1 wt. percent of potassium dichromate and 1 vol. percent of concentrated sulphuric acid without affecting the unexposed silver halide. After being treated with a 10 wt. percent sodium sulfite solution the unexposed silver halide is reduced by a usual black-and-white developer to which sodium hydroxide and hydrazine sulphate have been added.

The silver metal obtained in this reducing step is then bleached with an oxidizing agent as described above and the partially bleached silver image is color-developed according to the method of the present invention.

Although the process of forming color images according to the present invention preferably is carried out using a photographic color material containing diiferently sensitized silver halide emulsion layers, each containing a suitable color coupler, the process according to the present invention can also be applied with photographic materials containing mixed packet photographic silver halide emulsions. Emulsions of that type are described e.g. in our US. patent specification 3,000,740 and our Canadian patent specification 678,939.

Further it is now stated that the dyes obtained by oxidatively coupling according to the present invention can be metallized i.e. these dyes can be used as complexing agents for metal salts e.g. cobalt, nickel, chromium or iron salts, and in this way shifts in color can be obtained.

Any black-and-white developer may be used for the formation of the silver metal image, but preferably a combination of p-methylaminophenol and hydroquinone or a developer comprising 1-phenyl-3-pyrazolidinone is used.

Bleaching solutions, which are preferably used, have the following composition: 50 g. of copper (II) chloride and 10 cos. of acetic acid in 1000 cos. of water or 15 g. of potassium hexacyanoferrate (H1) in 1000 ccs. of water.

The color developing compositions used in the present invention for developing the bleached silver image contain preferably from 1 to 10 g. of the hydrazone per liter and have preferably a pH comprised between 8 and 12.

The following examples illustrate the present invention.

EXAMPLE 1' To 280 g. of a light-sensitive silver halide emulsion containing A5 mol of silver bromide and 8% by weight of gelatin, are successively added 45 ccs. of color coupler solution consisting of 4.5 g. of N-(2-n-hexadecylsulphonyl--sulphenophenyl)-1-hydroxy 2 napthoic acid amide sodium salt dissolved in a mixture of 40.5 cos. of water and 4.5 ccs. of 2 N sodium hydroxide.

developed for 7 min. at C. in a color developing solution of the following composition:

3-methyl-2-benzothiazolone-3-carboxy 4' hydroxyphenylsulphonyl-hydrazone prepared according to This emulsion is acidified with acetic acid to pH 6 5 preparation 3 4 and hardened with v1 cc. of a 10% aqueous chromium Sodium sulphite (anh.) 4 (III) sulphate solution. Distilled water containing a little Sodium carbonate usual wetting agent is added up to a total amount of emul- Water to -0 sion of 10 The developed material is rinsed for 2 min. in running This emulsion is Coated O b y P p P- water of 20 C. and bleach-fixed in a bath of the folport in such a way that 0.5 g. of color coupler is present lowing composition: per sq. m. G-

The dried emulsion layer is exposed behind a grey SOdmm-Iron (III) salt of ethylenedlamme tetraacetlc wedge and then black-and-white developed for 10 min. 15 at C. in a developing bath f the f ll i o Sodium salt of ethylenediamme tetraacetic ac1d 12.5 position: Ammonium thiosulphate (anh.)

Ammonium thiocyanate (anh.) 5 p-Methylaminophenol hemisulphate 0.5 20 ggg (anh') '10 Sodium sulphite (anh.) 20 act to Hydroquinone .1 After having been rinsed for .15 min. in running water Borax 0.5 of 20 C. a negative magenta wedge image is obtained Water to 100 having an absorption maximum at 530 mp.

25 The following table illustrates the absorption maxima,

The test inatenal is then m f which are obtained according to the process of Example water of 20 and bleached for 3 mm. in a solution of 1 by developing silver halide emulsion layers containing 15 of PQtaSSlllm hfixacyanoffl'fate 111 1000 Of a color coupler as indicated with ditferent hydrazone comwater. After a short rinsing, the bleached silver image is pounds.

TABLE Absorption maxima in m obtained with hydrazone compounds according to preparations- Colour coupler 1 2 3 4 6 6 7 8 na so;- CH,),5cH; 530 530 530 525 660 530 535 530 CO-NH HzC-(CHzha-N-OH; OH 540 535 540 520 670 620 535 540 SIG:

011 520 505 520 520 655 035 525 520 QG-co-Nn--so,-NH-(ommon,

SOr-(CHDu-CH; 455 460 455 510 460 455 so H n t H:C-C-NHCO SIOJH 430 420 430 480 440 403 EXAMPLE 2 cording to preparation 6 g 4 Sodium sulphite (anh.) g 4 Sodium carbonate (anh.) -g 50 1 N aqueous sodium hydroxide ccs 8 Water ccs. to 1000 The color-developed material is rinsed for 2 min. in

running water of 20 C. and the residual silver and silver salts are removed in a bleach-fixing bath of the composition given in Example 1.

After a min. rinsing in running water of 0., a negative blue wedge image is obtained having an absorption maximum at 630 m EXAMPLE 3 A photographic material prepared as described in Example 1 is exposed and black-and-white developed as described in Example 1.

The developed material is fixed for 2 min. in a 20% aqueous sodium thiosulphate solution and rinsed for 5 min. in running water of 20 C.

The material is then bleached for 2 min. in a bath of the following composition:

G. Potassium hexacyanoferrate ('III) 100 Borax 20 Boric acid 5 Water to 1000 ccs.

After 5 min. of rinsing, the processing is interrupted for 8 days and then continued in full day light without harm to the image quality by treating the material for 10 min. with the following solution:

G. 1,4 dimethyl 2 quinolone-3'-carboxy-4-hydroxyphenylsulphonyl-hydrazone prepared according to preparation 2 4 Sodium sulphite (anh.) 4

Sodium carbonate Water to 1000 ccs.

After 5 min. of rising, the silver metal is bleached for 5 min. in a solution of the following composition:

Potassium hexacyanoferrate (III) 50 Potassium bromide 1S Borax 10 Boric acid 13 Water to 1000 ccs.

The material is then rinsed for 2 min., fixed for 2 min. in a 20% aqueous solution of sodium thiosulphate, and finally rinsed again for 15 min. in running water of 20 C.

The obtained negative magenta wedge image absorbs at 530 my.

EXAMPLE 4 g 1 Sodium sulphite (anh.) g 1 5% aqueous sodium carbonate solution ccs.. 250

Then the material is bleach-fixed as described in Example 1 and rinsed for 5 min. in running water of 20 C.

The following table represents the used combination, the colors obtained and their absorption maxima.

TABLE Hydrazone compgilgnd accor g to p pa- 3 5212% ration Coupling component Colour m a 5 0 Ma euta..... 515

g CH;COCH;fi 1'? 5 S02(C r)15-CHs Cyan 670 we O-NH- 3 0 Yellow 41o CHsC O-CB'a-fii II? 3 0H Red- 505 TABLE-Continued Hydrazone compound according Absorption to prepamaximum, ration Coupling component Colour mg 3 ()H Red 495 3 0H Red 500 3.. B a-NH Red..-..... 505

3 Yellow...... 00

l 0:0 IfI H:(5-C-NH1 l O=C 1E? H:7--CCH;

3 H ..do...-.- 455 H?!) fiJH HC---CH 3.. NH; Magenta..-. 620

(JO-NH-CHr-CH -NH:

6.....-...... HQ do 560 TABLEContinued Hydrazone compound according Absorption to prepamaximum, ration Coupling component Colour mp. 6 SOa-IIIH Blue 615 6 Yellow 470 (30011 Q-NH-GO-OHn-CO NHCO(CHz)u-CH2 2 H Red 505 N-- 2 Blue 605 2 IFH: Yellow...-.. 470

1 80 E 2 C| H Red..-..-.. 510

/CzH5 N CgHg 2 SO -NH Magenta...- 535 2 (RH Bed 500 1103s NE-Q-OOOH EXAMPLE 5 Potassium dichromate 'g 1" A photographic material composed as described in Ex- Strong sulphuric acid cc 1 ample 1 is exposed and for min. black-and-white developed in a developing bath of the following composition:

Water to 1000 ccs.

The silver metal formed on said development is etched away by a treatment in a solution of the following composition:

Water to 1000 ccs.

without harm to the non-developed silver halide. After this treatment, the silver halide is reduced with a hydrazine-containing solution of the following composition:

Water to 1000 ccs.,

17 and thereafter rinsed for min. with running water.

These processing steps are described 'by W. Jolly, J. Chem. Educ. 39 (1962) 83.

By bleaching the obtained positive silver image and further processing as described in Example 1, a positive magenta image is obtained having an absorption maximum at 530 mu.

EXAMPLE 6 A red-sensitized silver halide emulsion is prepared as follows:

ccs. of a color coupler solution consisting of 1 g. of N-p-methylsulphonylaminoethyl-N-n-hexadecylaniline, dissolved in a mixture of 5 ccs. of 0.5 N sodium hydrox ide and 10 ccs. of ethanol, are added to 35 ccs. of a 4% aqueous gelatin solution, to which was previously added a little amount of a usual wetting agent.

The solution thus obtained is brought to pH 6 by adding acetic acid and then mixed with 50 g. of a light-sensitive silver halide emulsion layer containing mole of silver bromide and 8% by weight of gelatin. This emulsion is then sensitized by adding a solution of a redsensitizer.

A green-sensitized silver halide emulsion is prepared analogously by using as color coupler 1 g. of the sodium salt of N-(2-n-hexadecylsulphonyl-5'-sulphophenyl)-1- hydroxy-Z-naphthoic acid amide.

A blue-sensitive silver halide emulsion is prepared analogously by using as color coupler l g. of l-p-sulphophenyl-3-pentadecylpyrazolone(5).

To a cellulose acetate support provided on its back of an antihalation layer and on its front side with a subbing layer are applied successively the above red-sensitized silver halide emulsion layer, the above green-sensitized silver halide emulsion layer, a yellow filter layer consisting of colloidal silver dispersed in gelatin, and the above blue-sensitive silver halide emulsion layer.

The obtained photographic multicolor material is exposed through a multicolor negative and subsequently developed at 20 C. for 5 min. in a bath of the following composition:

G. p-Methylaminophenol hemisulphate 0.75 Anhydrous sodium sulphite Hydroquinone 3 Anhydrous sodium carbonate 16 Potassium bromide 1 Water to make 1000 ccs.

G. 3 methyl 6 methoxy-Z-benzothiazolon-3-carboxy- 4 hydroxyphenylsulphonylhydrazone of preparation 9 4 Anhydrous sodium sulphite 4 Anhydrous sodium carbonate 50 Water to make 1000 ccs.

The developed material is rinsed for 5 min. in running water and bleached for 2 min. in a bath of the following composition:

Hydrated copper sulphate g 100 Sodium chloride g 100 Strong sulphuric acid ccs 25 Water to make ccs 1000 After having been rinsed for 2 min. in running water, the material is fixed for 2 min. in 20% aqueous sodium thiosulphate and rinsed for 10 min. in running water. A multicolour positive image is obtained consisting of the complementary colours of the negative original.

What I claim is:

1. A method of producing a colored image by developing a bleached silver image still containing silver nuclei, characterized thereby that the development is carried out by oxidatively coupling of a color coupler with a hydrazone compound dissolved in an alkaline aqueous medium and that said hydrazone compound contains in its formula the following structural part:

I wherein:

n is a positive integer from 1 to 3,

R is hydrogen or an acyl radical, and

R is a .-CONH or a SO X group, wherein X represents a hydroxyl group or an amino radical, aliphatic hydrocarbon radical, aryl radical, or heterocyclic radical.

2. In a method of producing a colored image the steps of exposing a photographic material containing lightsensitive silver halide, developing said material by means of a 'black-and-white developer, bleaching the obtained silver image to a silver salt image still containing silver nuclei and the silver salts of which have a solubility prodnot of 10* to 10 at 25 C., and developing the thus treated material in an alkaline aqueous solution containing in dissolved state a hydrazone compound, which forms a colored product with a color coupler either present in the material before bleaching or present in dissolved state in said alkaline aqueous solution, at the areas where the silver was bleached, said hydrazone compound being characterized by the following structural part:

wherein:

n is a positive integer from 1 to 3,

R is hydrogen or an acyl radical, and

R is a CONH or a SO X group, wherein X represents a hydroxyl group or an amino radical, ali phatic hydrocarbon radical, aryl radical, or heterocyclic radical.

3. In a method of producing a colored image according to claim 2, the hydrazone compound being represented by one of the following general formulae:

Z represents the non-metallic atoms necessary to complete a 5- or 6-membered heterocyclic nucleus, alone or making part of a condensed ring system,

R is hydrogen or an acyl radical,

R is a --CONH group or a SO X group, wherein X represents a hydroxyl group, an amino radical, an aliphatic hydrocarbon radical, an aryl radical, or a heterocyclic radical,

R is a hydrogen atom, an alkyl radical, or an aryl radical,

R; is a hydrogen atom, an alkyl radical, or an aryl radical,

R is an amino radical, a heterocyclic radical, or a hydrocarbon radical,

R and R each represents the same or different substituents of the group consisting of hydrogen, halogen and dialkylamino, carbethoxy, cyano, alkoxy, alkyl and aryl radicals or represent together the atoms necessary to close a 5- or 6-membered homocyclic ring, and

Y represents the non-metallic atoms necessary to complete a nitrogen-containing heterocyclic nucleus, said hydrazone compound having substituted thereon sufficient ionic radicals of the radicals defined above to make the same soluble in an alkaline aqueous medium.

4. In a method of producing a colored image according to claim 3, the color coupler being present in a lightsensitive silver halide emulsion layer.

5. In a method of producing a colored image according to claim 4, the color coupler being a coupler of the non-migratory type of the naphthol-, phenol-, pyrazolone-, or ketomethylene type.

'6. In a method of producing a colored image according to claim 3, the bleaching being carried out by means of an aqueous solution containing hexacyanoferrate (III) ions.

7. In a method of producing a colored image according to claim 3, the bleaching being carried out by means of an aqueous solution containing copper (II) chloride.

References Cited UNITED STATES PATENTS 2,163,325 6/1939 Sanders-Dolgoruki 9122 2,494,068 1/1950 Speck 96-60 J. TRAVIS BROWN, Primary Examiner.

A. T. SUROPICO, Assistant Examiner.

US. Cl. X.R. 96-76; 250-65 

